Problem connecting external extension - firewall config

Discussion in '3CX Phone System - General' started by ste111, Jul 6, 2009.

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  1. ste111

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    Hello,

    I have a working test environment with asterisk. The environment looks like this:

    asterisk (192.168.3.9) <-> Juniper Firewall (SIP-ALG, 192.168.3.254) <-> Router (NAT) <-> Snom 360 (without STUN)

    I can call extension attached to asterisk internal and I can call the external Snom.

    I tried the same with 3CX instead of asterisk. The phones can register without problems. The external phone can call but can't be called no matter with or without STUN.

    Firewall-Cecker says that everthing is OK.

    I have a working sip trunk to sipgate.de.

    Is there anyone who could give me hints how to fix this?

    Thanks in advance

    Stephan
     
  2. leejor

    leejor Well-Known Member

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    Re: Problem connecting external extension - works with asterisk

    Is the external phones port (5060?) forwarded in the remote router to it's (fixed) IP?
     
  3. ste111

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    Re: Problem connecting external extension - works with asterisk

    Hello leejor,

    with asterisk there is no need to forward port.

    I tried so many different configuration that I'm totally confused and frustrated because it works with asterisk easily.
     
  4. discovery1

    discovery1 Member

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    Re: Problem connecting external extension - works with asterisk

    You will need to open ports 9000 to 9100 inbound on the firewall and forward them to the 3CX machine. If you don't want to forward ports then use asterisk.

    But your on a 3CX forum asking for help, so try the things we are suggesting and I'm sure we will be able to help you in getting it working.
    Also run the firewall checker and see if there are any other errors that it shows you.
     
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  5. leejor

    leejor Well-Known Member

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    Re: Problem connecting external extension - works with asterisk

    So... the 3CX logs are showing the remote set registering. During registration, do they show the correct (public) IP and port that the phone is actually using? If that info isn't correct then 3CX won't be able to get a call through even if you can make an outgoing call. What does a log look like when you attempt a call to the set? What sort of failure do you get?
     
  6. reticent

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    Re: Problem connecting external extension - works with asterisk

    Hi folks, I know its been a while since the last post but was hoping that someone could update the strand to let me know the solution.

    i am experiancing the same issue. I can receive the call from the external extn and hear the voice clearly. However they can not hear me and when i try to initate the call from my end (internal) i am unable to connect.

    I can confirm that the ports are already open. 9000-9049 to be exact.

    Any help would be appreciated..
     
  7. KerryG

    KerryG Active Member

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    Re: Problem connecting external extension - works with asterisk

    One way audio is almost always a sign of a firewall/NAT issue. You would need to post some verbose logs of the calls so that people can see what is happening. Its likely that the phone isn't sending the public IP address in the invite or some other strange behavior. This can often be fixed by configuring stun on the phone. You also want to run the firewall check and make sure it isn't throwing any errors.
     
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  8. houston

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    Re: Problem connecting external extension - works with asterisk

    Apparently there may be an issue with 3cx & Snom working when 3cx is behind NAT.

    If anyone HAS the combo working (3cx behind NAT, Snom on public IP) could you reply back with your model phone and firmware? It would help me tremedously.

    Thanks!
     
  9. KerryG

    KerryG Active Member

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    Re: Problem connecting external extension - works with asterisk

    Certainly the easiest test is to use another phone or softphone to be able to pin the issue on the snom.
     
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  10. comresource

    comresource Member

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    Re: Problem connecting external extension - works with asterisk

    I have a snom300 that works ok with both phone and 3cx are behind seperate NAT, Is your problem specific to the snom having a public IP?
     
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  11. tpinnovations

    tpinnovations Member

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    Re: Problem connecting external extension - works with asterisk

    If that router supports UPNP turn it off, it may be hijacking the routing table.
     
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  12. reticent

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    Re: Problem connecting external extension - works with asterisk

    Hi all,

    Got it working using the "3CX proxy SIP Tunnel" software running on a desktop at the remote end. Will test if i can setup the proxy manager localy but dont see it working. Will leave a post afterwards if i am successful. Here is the link you need: http://wiki.3cx.com/documentation/networking/sip-proxy-manager

    Using 3CX with a Yealink T22P remotely behind a NAT. As per link, installed proxy manager on a desktop remotely and it worked fine. The same settings on the 3CX client didnt work however once the proxy manager was installed it worked fine.

    uPnP is turned off on the router and i have also disabled SIP ALG (both ends)

    Ports open on the local router are:
    1 SIP Service 5060 - 6060
    2 Stun Server 3478
    3 3CX Tunnel 5090
    4 Line Out 9000 - 9049
    5 3CX Proxy 5080

    No ports on the remote router are open however windows firewall needs to have port 5080 (which ever one you use) open to allow phone to talk.

    On The remote T22P:
    Enable Outbound Proxy Server = "Enabled"
    Outbound Proxy Server= "IP Address of pc that has the proxy software installede" port = "Proxy port"

    I hope this helps.
     
  13. smb1

    smb1 New Member

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    Re: Problem connecting external extension - works with asterisk

    I can confirm similar behaviour with a Yealink T22P remote extension and a Yealink T28. Either calls would not complete or one-way audio. 3CX Voip Phone had similar results when using remote settings, but would work if Tunnel mode enabled.

    Using the 3CX Tunneling Proxy allowed 2 way audio and calls completed successfully.
     
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  14. Nick Galea

    Nick Galea Site Admin

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    THis is 100% a firewall configuration problem. You need to run the firewall checker, ensure its OK or use the tunnel.

    You will have problems with any SIP solution you use if you do not properly configure your firewall.
     
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  15. smb1

    smb1 New Member

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    Nick,

    Firewall checker runs without error.

    WIll trying to run remote extensions for one 3cx installation at a site that also has a local 3cx installation for another client cause issues? I can see the potential for port mapping conflicts.

    David Benet
    SMB Technology
    Melbourne Australia
     
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